The overall objectives of this proposal are 1) to determine the mechanisms which, following a meal, increase blood flow to the digestive organs, maintain flow unchanged in the heart and kidney while reducing flow to skin and muscle, and 2) to elucidate the participation of absorptive processes of nutrients, intestinal nerves and locally released chemicals and hormones in the control of these cardiovascular responses. The proposed work is as follows: (1) Food constituents that increase intestinal blood flow will be identified by measuring the blood flow through the jejunum as various food constituents are placed, separately or in combination, into the lumen. (2) Food constituents will also be infused intra-arterially to various organs to determine their vasoactivity. (3) The influence of the absorptive process on the hyperemia will be determined by comparing the blood flow effects of various nutrients having different absorptive processes and by measuring intestinal blood flow before and after inhibition of absorption. (4) The participation of locally released chemicals will be determined by testing for changes in the vasoactivity of jejunal blood during luminal placement of nutrients. Jejunal venous blood will be assayed by pumping it through other organs at constant flow rate while measuring perfusion pressure. (5) If the vasoactivity of the jejunal venous blood is altered, we will assay for certain vasoactive substances (e.g., adenine nucleotides) by chemical methods. (6) The participation of neural input will be studied by topical anesthesia of the mucosa and by local infusion of a neurotoxin or blocking drug. The effects of nutrients on local blood flow will be tested before and after neural blockade. Oxygen consumption of the intestine will be measured in the first, third, fourth and sixth studies of the above works so that relation of blood flow and metabolism can be elucidated.